refactor: remove unused event listener cleanup and enhance focus target selection logic

Author: jrmartin

applications/virtual-fly-brain/frontend/src/components/StackViewerComponent.jsx

@@ -1806,9 +1806,6 @@ const StackViewerComponent = () => createClass({
     },
 
     componentWillUnmount: function () {
-      if (this._wheelListenerElem && this._wheelListenerCallback) {
-        this._wheelListenerElem.removeEventListener(support, this._wheelListenerCallback);
-      }
       this._isMounted = false;
       return true;      
     },

applications/virtual-fly-brain/frontend/src/reducers/middleware/urlUpdaterMiddleware.js

@@ -77,7 +77,9 @@ const isFirstTimeLoad = (allLoadedInstances, store) => {
       store.dispatch(setBulkLoadingCount(instancesToLoad.length));
     }
 
-    const focusTarget = idSelected || uniqueLoadOrder[uniqueLoadOrder.length - 1];
+    const focusTarget = queuedInstances.length > 0
+    ? queuedInstances[queuedInstances.length - 1]
+    : (idSelected || uniqueLoadOrder[uniqueLoadOrder.length - 1]);
 
     uniqueLoadOrder.forEach(id => {
       const shouldFocus = id === focusTarget;